Implantable medical devices (IMDs) typically include connector modules for the coupling of implantable medical leads to the devices; the medical leads include elongated bodies extending from a proximal connector and carrying conductors for delivery of therapy from the IMD to a selected site within a body of a patient. One type of therapy most commonly delivered through such leads is electrical stimulation therapy; therefore electrical contacts are formed on the lead connector to make electrical connection, within the connector module, between the conductors of the lead and the IMD. It should be noted that leads and devices may also be implanted solely for the purpose of diagnostic monitoring, wherein electrical contacts are also elements of the lead connector, or for the purpose of therapeutic agent infusion, wherein electrical contacts are not required elements. For the purposes of this application, reference will be made only to a pacemaker IMD and lead, it being understood that the principles herein may have applicability to a host of other medical systems.
Once a cardiac lead has been implanted such that one or more electrodes are in contact with cardiac tissue, the connector of the lead is inserted into an IMD connector module bore containing one or more electrical connectors that are configured to engage with one or more contacts located on the lead connector. Both electrical and fluid tight seals are required between each electrical contact and between the lead connector, within the bore, and the implant environment outside the bore. Sealing rings, mounted either on the lead connector or within the bore, create such seals, however it has been found that the seals may make full insertion of the lead connector difficult due to pressure build-up within the bore once a first set of sealing rings engages between the lead connector and the bore. Accordingly, there is a need for a device connector module assembly that relieves or vents this pressure.